Aiming systems are currently made with light emitting diodes (LEDs) and laser diodes that project particular light shapes aimed to clearly indicate where a device field of view (FOV) occurs. The current state of the art can be divided into two groups: Single light source devices; and double light source devices.
“Single light source” aiming systems are typically designed to project a well-defined figure that tries to indicate the center or other features of the FOV. The main limitation of this approach is that the origin of this source cannot stay in the optical axis of the device and then the projected figure may indicate only approximately the real center of the FOV. In particular, the error is higher, in relation to the width of the FOV, at short distances.
“Double light sources” aiming systems can overcome the limitations of the “single light source” aiming systems by exploiting two principles, symmetry and overlap of figures. In the case of symmetry, “double light sources” aiming systems achieve symmetrical configurations with respect to the optical axis. In this way, it is possible to generate a symmetrical figure with respect to the center of the FOV, which makes it easily identifiable. An example of the “double light sources” is the combination of two parallel laser pointers arranged symmetrically to the optical axis. The FOV center is always in the midpoint of the two laser images. Regarding the overlap principle, two light sources can overlay two figures in order to highlight some specific points of the FOV. An example of this approach is where two laser lines, which lie in the same plane, intersect each other on the optical axis and generate a cross pattern in the center of the FOV. This type of aiming system is better than a single light source aiming system, but it has the drawback of including additional hardware, increasing product costs and decreasing compactness.